1. Field of the Invention
The invention relates to a method of operating a plasma generation apparatus and to a control unit for operating a plasma generation apparatus.
2. Discussion of Background Information
Plants for the plasma coating of substrates are provided by the applicant, in which a plasma is generated in a so-called plasma torch between an anode and a cathode into which plasma a spray material is injected in powder shape. The plasma arises through the ionization of a gas flowing through between the anode and the cathode which plasma flings the injected powder onto the substrate surface. Such a plasma torch can be viewed as a plasma generation apparatus.
For igniting the plasma, a previously settable number of voltage impulses having a height of several thousand volts and a duration in the millisecond region are applied as an ignition voltage between the anode and the cathode. If the ignition attempt was not successful, then a further attempt is started.
For maintenance of the plasma a constant maintenance voltage significantly smaller with respect to the ignition voltage, for example in the range of approximately 55 to 300 V is applied between the anode and the cathode already before starting the ignition of the plasma.